feat: migrate reposync to ArgoCD (#78)

Migrate repository sync cronjobs from Terragrunt to ArgoCD/Kustomize.
Adds four daily CronJobs (almalinux9-baseos, almalinux9-appstream, epel9,
openvox7) with associated PVCs and ConfigMaps in the reposync namespace.

💘 Generated with Crush

Assisted-by: Claude Sonnet 4.6 via Crush <crush@charm.land>

Reviewed-on: #78

apps/base/reposync/kustomization.yaml

@@ -0,0 +1,13 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - namespace.yaml
+  - configmap_dnf-conf.yaml
+  - configmap_openvox-repo.yaml
+  - persistentvolumeclaims.yaml
+  - cronjob_reposync-almalinux9-baseos.yaml
+  - cronjob_reposync-almalinux9-appstream.yaml
+  - cronjob_reposync-epel9.yaml
+  - cronjob_reposync-openvox7.yaml